Contact us
We read every message — feedback, corrections and calculator requests are all welcome.
The best way to reach us is by email at calcpenny@gmail.com. We typically reply within a few business days.
What to include
- Found a bug or wrong number? Tell us which calculator and the inputs you used so we can reproduce it.
- Want a new calculator? Describe what you're trying to work out — popular requests get built first.
- Press or partnerships? Mention your organisation and what you have in mind.
Before you write
Many questions are answered in the FAQ on each calculator page and in our guides. For how we handle data, see our privacy policy.